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This Week in PLOS: Feb 4, 2013

In PLOS Neglected Tropical Diseases, INSERM researcher Michel Drancourt and colleagues from France, Senegal, the UK, Ethiopia, and Australia describe a multiplex, real-time PCR approach for blood-based detection of Borrelia pathogens that cause relapsing fever in Africa. The team used genomic information to select a set of genes for detecting — and starting to distinguish between — four fever-causing Borrelia species transmitted by arthropods such as ticks or body lice. In proof-of-principle experiments presented in the paper, a multiplex, real-time PCR test based on a Borrelia 16S ribosomal RNA gene and three other genes was 100 percent sensitive and specific for detecting B. hispanica or B.duttonii/B. reccurentis and 99 percent sensitive and specific for finding B. crocidurae. Based on these results, study authors say the test shows point-of-care promise "to confirm diagnosis and provide evidence of the burden of infection attributed to different species of known or potentially novel relapsing fever borreliae."

A broad range of drug resistant tuberculosis-causing bacterial lineages exist in Saudi Arabia, though the strains infecting individuals born in that country tend to overlap with those found in more recent immigrants, according to a phylogenetic study in PLOS One. Researchers based in Saudi Arabia and France used a mycobacterial interspersed repetitive unit-variable number of tandem repeat, or MIRU-VNTR, test based on 24 loci to genotype 322 drug resistant Mycobacterium tuberculosis isolates collected in the clinical setting in Saudi Arabia over the course of a year. The "substantial admixture" they identified points to "substantial ongoing [tuberculosis] transmission between population groups," study authors say, pointing to the need for "more vigorous surveillance and adherence to [tuberculosis] control policies in the country."

A Pennsylvania State University-led team took what it calls a "phenome-wide association study," or PheWAS, approach to finding new genetic architecture and pleiotropic genetic effects in four different human populations. As they report in PLOS Genetics, the researchers brought together data on SNPs previously identified in genome-wide association studies with information on more than 4,700 phenotypes for more than 70,000 individuals enrolled in the Population Architecture using Genomics and Epidemiology, or PAGE, network. Using this approach, study authors say, "We replicated a number of previously reported associations, validating the PheWAS approach. We also identified novel genotype-phenotype associations possibly representing pleiotropic effects." For instance, the analysis suggested that a risk SNP linked to high-density lipoprotein levels in European Americans is also related to additional heart and calcium-related phenotypes in the same population and to hypertension in African Americans.